The present invention relates to transmission-receiving techniques and recording-reproduction techniques for signals between apparatuses, or more in particular to an output circuit, a recording apparatus and a reproduction apparatus for digital video signals, in which the digital information signal for moving pictures, programs or the like transmitted by transmission means such as coaxial cable, optical cable, telephone channel or satellite broadcast are received and the received signals are exchanged between apparatuses.
A recording-reproduction apparatus for digital video signals is disclosed, for example, in JP-A-1-258255 (U.S. Pat. No. 5,065,259).
Also, an ITU-T Draft Rec. H.262 standard called MPEG-2 (Moving Picture Experts Group) is known as a scheme for digitally compressing the video signal at high efficiency. On the other hand, a MPEG-2 Systems Working Draft is known as a transmission standard for the video signal and the audio signal compressed by MPEG-2.
The above-mentioned standards present a technique for compressing a program and broadcasting it digitally. The use of this compression scheme with a high compression ratio allows broadcasting of four to eight times more programs than the conventional analog broadcast in the same transmission channel. As a result, a digital satellite service or a similar service called the Near Video On-Demand in which moving pictures of two hours are broadcast repeatedly in 30 minute shifts, for example, has already started in the U.S. Since all programs cannot be broadcast by the Near Video On-Demand service throughout the day, however, there still is a demand for video-recording broadcast signals and viewing programs by playback at convenient times as in the prior art.
A method for recording and reproducing a program which is digitally compressed and digitally broadcast may include decompressing the received digital signal and after converting it into an analog signal, recording it in the conventional analog VTR. The conversion into an analog signal and video-recording by analog VTR spoils the valuable high signal-to-noise ratio of the digital signal.
JP-A-1-258255 discloses a technique for A/D converting an analog video signal input and digitally recording it after bit reduction. In the case of digital broadcasting, however, a high-efficiency digital compression is already employed, and therefore, the decompression and digital recording of the signal as disclosed in the aforementioned publication JP-A-1-258255 fails to obtain a sufficient compression efficiency, or the use of such a high-efficiency digital compressor as used in broadcasting stations for each VTR has a great cost.
It is desired to digitally record the digitally broadcast signal directly. According to the aforementioned MPEG standard, for example, a signal is compressed and the compressed signal is transmitted as packets in a transport stream format. Nevertheless, any technique for recording the digital signal thus transmitted is not yet disclosed.
A digital signal recording apparatus for recording a digitally compressed video signal on the magnetic tape using a rotary head is disclosed in JP-A-5-174496. Measures against recording signals of different transmission rates and signals of different types are not taken into consideration by such an apparatus.